Practical benefits of the continuous load monitoring ultrasonic contact impedance (UCI) hardness testing method


Since its development in 1961, the ultrasonic contact impedance (UCI) method has been widely used in portable hardness testing. The relatively high user dependence is a well-known disadvantage of the manually-operated UCI method, when compared to other portable hardness testing methods (for example Leeb). However, equipping UCI probes with an internal force sensor allows for continuous monitoring of the manually applied force, enabling the system to provide user guidance during the measurement. Furthermore, this allows multi-measurement, ie multiple hardness readings during the loading process of one contact point, a feature that provides information on additional properties of the test-piece, such as homogeneity and thickness of the hardened layer. In this paper, we present the validation of this concept, a study of the influence of the system’s parameters on measuring with UCI, as well as an overview of the improvements to the UCI method that can be achieved with these new features.